Gear pair shafting mechanisms in a gear box are universally utilized in the form of a hub which is displaced on a splined shaft to engage a selected gear. The shifting mechanism can have a rotation synchronizing device to provide for the engagement without clashing of the teeth. During a speed change, i.e. a change of the selected gear pair for the operation, which change is made with the machine or vehicle running or moving, a synchronization of the movements of the parts of the transmission is required.
These mechanisms have been largely utilized in mechanical industries and in automotive transmissions. Mechanisms with synchronizing rings are largely used and well known. An example of such shifting mechanisms with synchronizing rings is disclosed in a publication of the SAE (Society of Mechanical Engineers) under number 680008, published in January, 1968.